Event related frequencies (ERFs) offers a noninvasive method for evaluating cognitive function by providing information on the speed and location of stimulus processing at the cortical level. The initial goal is to test a unique method of quantifying cognitive brain frequency domain activity for the purpose of discriminatory diagnostic testing and neurophysiologic monitoring of brain dysfunction. Eventual goals involve refining data acquisition for establishing correlates of patterns with specific neurologic manifestations such as Alzheimer's, AIDS, trauma and normal aging. Phase I, a pilot study, tests thirty adults - ten normal and 20 Alzheimer's patients (10 borderline [Mini-Mental Status 24-26] and 10 moderate [MMS 15-23]. Objectives are: 1) acquire dynamic recordings of electrical frequency shifts in the millisecond range resulting from processing of complex stimuli, 2) analyze data and 3) refine software. Phase II proposes longitudinal comparison between Alzheimer's patients and normal aging, establishment of decade normals, data acquisition expansion to other brain dysfunctions and continued software refinement for expanded clinical and commercial application. A method of measuring changes in cerebral organic dysfunction and response to treatment will facilitate both earlier diagnoses and drug research offering significant health care and financial rewards.